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Amplification of human platelet activation by surface pannexin-1 channels

BACKGROUND: Pannexin-1 (Panx1) forms an anion-selective channel with a permeability up to ∼1 kDa and represents a non-lytic, non-vesicular ATP release pathway in erythrocytes, leukocytes and neurons. Related connexin gap junction proteins have been reported in platelets; however, the expression and...

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Autores principales: Taylor, K A, Wright, J R, Vial, C, Evans, R J, Mahaut-Smith, M P
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BlackWell Publishing Ltd 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4238786/
https://www.ncbi.nlm.nih.gov/pubmed/24655807
http://dx.doi.org/10.1111/jth.12566
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author Taylor, K A
Wright, J R
Vial, C
Evans, R J
Mahaut-Smith, M P
author_facet Taylor, K A
Wright, J R
Vial, C
Evans, R J
Mahaut-Smith, M P
author_sort Taylor, K A
collection PubMed
description BACKGROUND: Pannexin-1 (Panx1) forms an anion-selective channel with a permeability up to ∼1 kDa and represents a non-lytic, non-vesicular ATP release pathway in erythrocytes, leukocytes and neurons. Related connexin gap junction proteins have been reported in platelets; however, the expression and function of the pannexins remain unknown. OBJECTIVE: To determine the expression and function of pannexins in human plate-lets, using molecular, cellular and functional techniques. METHODS: Panx1 expression in human platelets was det-ermined using qPCR and antibody-based techniques. Contributions of Panx1 to agonist-evoked efflux of cytoplasmic calcein, Ca(2+) influx, ATP release and aggregation were assessed in washed platelets under conditions where the P2X1 receptor response was preserved (0.32 U mL(−1) apyrase). Thrombus formation in whole blood was assessed in vitro using a shear chamber assay. Two structurally unrelated and widely used Panx1 inhibitors, probenecid and carbenoxolone, were used throughout this study, at concentrations that do not affect connexin channels. RESULTS: PANX1, but not PANX2 or PANX3, mRNA was detected in human platelets. Furthermore, Panx1 protein is glycosylated and present on the plasma membrane of platelets, and displays weak physical association with P2X1 receptors. Panx1 inhibition blocked thrombin-evoked efflux of calcein, and reduced Ca(2+) influx, ATP release, platelet aggregation and thrombus formation under arterial shear rates in vitro. The Panx1-dependent contribution was not additive to that of P2X1 receptors. CONCLUSIONS: Panx1 is expressed on human platelets and amplifies Ca(2+) influx, ATP release and aggregation through the secondary activation of P2X1 receptors. We propose that Panx1 represents a novel target for the management of arterial thrombosis.
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spelling pubmed-42387862014-11-28 Amplification of human platelet activation by surface pannexin-1 channels Taylor, K A Wright, J R Vial, C Evans, R J Mahaut-Smith, M P J Thromb Haemost Platelets BACKGROUND: Pannexin-1 (Panx1) forms an anion-selective channel with a permeability up to ∼1 kDa and represents a non-lytic, non-vesicular ATP release pathway in erythrocytes, leukocytes and neurons. Related connexin gap junction proteins have been reported in platelets; however, the expression and function of the pannexins remain unknown. OBJECTIVE: To determine the expression and function of pannexins in human plate-lets, using molecular, cellular and functional techniques. METHODS: Panx1 expression in human platelets was det-ermined using qPCR and antibody-based techniques. Contributions of Panx1 to agonist-evoked efflux of cytoplasmic calcein, Ca(2+) influx, ATP release and aggregation were assessed in washed platelets under conditions where the P2X1 receptor response was preserved (0.32 U mL(−1) apyrase). Thrombus formation in whole blood was assessed in vitro using a shear chamber assay. Two structurally unrelated and widely used Panx1 inhibitors, probenecid and carbenoxolone, were used throughout this study, at concentrations that do not affect connexin channels. RESULTS: PANX1, but not PANX2 or PANX3, mRNA was detected in human platelets. Furthermore, Panx1 protein is glycosylated and present on the plasma membrane of platelets, and displays weak physical association with P2X1 receptors. Panx1 inhibition blocked thrombin-evoked efflux of calcein, and reduced Ca(2+) influx, ATP release, platelet aggregation and thrombus formation under arterial shear rates in vitro. The Panx1-dependent contribution was not additive to that of P2X1 receptors. CONCLUSIONS: Panx1 is expressed on human platelets and amplifies Ca(2+) influx, ATP release and aggregation through the secondary activation of P2X1 receptors. We propose that Panx1 represents a novel target for the management of arterial thrombosis. BlackWell Publishing Ltd 2014-06 2014-06-10 /pmc/articles/PMC4238786/ /pubmed/24655807 http://dx.doi.org/10.1111/jth.12566 Text en © 2014 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis http://creativecommons.org/licenses/by-nc/3.0/ This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
spellingShingle Platelets
Taylor, K A
Wright, J R
Vial, C
Evans, R J
Mahaut-Smith, M P
Amplification of human platelet activation by surface pannexin-1 channels
title Amplification of human platelet activation by surface pannexin-1 channels
title_full Amplification of human platelet activation by surface pannexin-1 channels
title_fullStr Amplification of human platelet activation by surface pannexin-1 channels
title_full_unstemmed Amplification of human platelet activation by surface pannexin-1 channels
title_short Amplification of human platelet activation by surface pannexin-1 channels
title_sort amplification of human platelet activation by surface pannexin-1 channels
topic Platelets
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4238786/
https://www.ncbi.nlm.nih.gov/pubmed/24655807
http://dx.doi.org/10.1111/jth.12566
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